I. Field of the Invention
This invention relates generally to electrosurgical instruments, and more particularly to a bipolar scissor having an embedded electrode. The bipolar scissor may be used in a laparoscopic procedure, or any other desirable endoscopic procedure.
II. Discussion of the Prior Art
In the conventional art, heat has been used for the cauterization of bleeding wounds in various surgical procedures. For example, the use of radio frequency (RF) energy traveling through the body has been widely used to stop bleeding. In this regard, at least two modes of cauterization are typically employed, namely monopolar or bipolar coagulation.
The prior art monopolar surgical instruments usually include a generator, an active electrode of small dimensions, and a large area return or dispersive electrode designed to be placed on the patient's body to serve as a return point for the energy released at the active electrode site. In this regard, the active electrode is applied to the bleeding site and the current path is completed through the body to the return electrode which is electrically in contact with the patient's body.
Bipolar surgical instruments have an inherent advantage over monopolar surgical instrument of containing energy generated at the surgical instrument. In a bipolar surgical instrument, both the active and the return electrodes are placed on the surgical instrument. Thus, no separate return electrode on the patient is required as in monopolar systems. Therefore, the generated energy remains at the site where the surgical instrument is being used and only affects patient tissue in close proximity.
Some bipolar scissors allow simultaneous cautery and cutting of tissue. Typically the base construction of the blades is metal with a layer of insulating material located on one of the shearing surfaces and the hinge pin to provide electrical isolation between the bipolar electrodes. A later advancement on this basic approach was to provide a layer of insulation between the base metal blade and a thin metal shearing surface to provide electrical isolation between the bipolar electrodes and allow for a more durable shearing surface.
The conventional art also discloses a base construction of ceramic material instead of metal with a metal coating applied to the outside edge of the ceramic body to act as the electrosurgical electrode. Additionally, the conventional art also discloses a laminated design that uses a base construction of ceramic material with metal applied to both the outside edge of the ceramic body to act at the electrosurgical electrode and the inside edge of the ceramic body to serve as the shearing surface. However, the conventional art laminated design may be structurally compromised when laminating materials having different material properties. For example, material characteristics such as thermal expansion and contraction properties may result in a laminated scissor (or blade) being weakened due to stresses caused by expansion and contraction of the composite materials.